In the disclosure of the present invention reference is mostly made to drug delivery devices comprising a threaded piston rod driven by a rotating drive member, such devices being used e.g. in the treatment of diabetes by delivery of insulin, however, this is only an exemplary use of the present invention.
Drug Injection devices have greatly improved the lives of patients who must self-administer drugs and biological agents. Drug Injection devices may take many forms, including simple disposable devices that are little more than an ampoule with an injection means or they may be durable devices adapted to be used with prefilled cartridges. Regardless of their form and type, they have proven to be great aids in assisting patients to self-administer injectable drugs and biological agents. They also greatly assist care givers in administering injectable medicines to those incapable of performing self-injections.
A general type of drug delivery devices suitable for delivery of a user set amount of drug comprises a spring which is strained during dose setting, the stored energy subsequently being used to expel the set dose of drug from a cartridge arranged in the device, this providing what can be termed an automatic drug delivery device in contrast to a traditional manual drug delivery device in which the set dose of drug is expelled by the user applying an axial force to a proximally extending push button. The user usually strains a spring by rotating a rotatable dose setting member, the force thereby applied by the user being stored in the spring for later release.
Performing the necessary insulin injection at the right time and in the right size is essential for managing diabetes, i.e. compliance with the specified insulin regimen is important. In order to make it possible for medical personnel to determine the effectiveness of a prescribed dosage pattern, diabetes patients are encouraged to keep a log of the size and time of each injection. However, such logs are normally kept in handwritten notebooks, and the logged information may not be easily uploaded to a computer for data processing. Furthermore, as only events, which are noted by the patient, are logged, the note book system requires that the patient remembers to log each injection, if the logged information is to have any value in the treatment of the patient's disease. A missing or erroneous record in the log results in a misleading picture of the injection history and thus a misleading basis for the medical personnel's decision making with respect to future medication. Accordingly, it may be desirable to automate the logging of injection information from medication delivery systems.
Though some injection devices integrate this monitoring/acquisition mechanism into the device itself, e.g. as disclosed in US 2009/0318865 and WO 2010/052275, most devices of today are without it. The most widely used devices are purely mechanical devices being either durable or prefilled. The latter devices are to be discarded after being emptied and so inexpensive that it is not cost-effective to build-in electronic data acquisition functionality in the device it-self. Addressing this problem a number of solutions have been proposed which would help a user to generate, collect and distribute data indicative of the use of a given medical device.
For example, WO 2014/037331 describes in a first embodiment an electronic supplementary device (also named “add-on module” or “add-on device”) adapted to be releasably attached to a drug delivery device of the pen type. The device includes a camera and is configured to perform optical character recognition (OCR) on captured images from a rotating scale drum visible through a dosage window on the drug delivery device, thereby to determine a dose of medicament that has been dialed into the drug delivery device. WO 2014/037331 also describes a second embodiment of an electronic supplementary device adapted to be releasably attached to a drug delivery device of the pen type comprising a drive screw extending proximally from the device corresponding to a set dose. The supplementary device comprises sensor means for determining axial extension of the drive screw as well as sensor means for detecting operation of the proximal delivery button. WO 2014/020008 discloses an electronic supplementary device adapted to be releasably attached to a drug delivery device of the pen type. The device includes a camera and is configured to determine scale drum values based on OCR. To properly determine the size of an expelled dose the supplementary device further comprises additional electromechanical sensor means to determine whether a dose size is set, corrected or delivered. A further external device for a pen device is shown in WO 2014/161952.
WO 2017/013463 discloses an add-on dose control system to be used in combination with a pen-formed drug delivery device, the dose control system being adapted to be mounted on the drug delivery device and comprising a magnetic component adapted to rotate during use of the drug delivery device, as well as magnetic detection means adapted to process information from the magnetic component in order to determine a set or expelled dose amount of drug.
US 2006/0175427 discloses a pen-formed drug delivery device provided with a position sensor comprising a magnetic ring coupled to a setting element and a number of magnetic switches allowing an angular position of the magnetic ring to be determined. In an exemplary embodiment a rotation of 45 degrees can be detected.
US 2015/0352288 discloses a medical injection system with dose capturing means in the form of a magnetic linear encoder comprising a multi-pole magnetic ring and a magnetic sensor in the form of a Hall element.
Having regard to the above, it is an object of the present invention to provide systems, devices and methods allowing secure, easy and efficient operation of a drug delivery system, of the automatic type comprising an indicator element and a sensor system adapted for capturing of dose related data. The system may be in the form of an assembly comprising a drug delivery device and an add-on device adapted to be releasably mounted on the drug delivery device.